Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762196AbXF0Pyk (ORCPT ); Wed, 27 Jun 2007 11:54:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755721AbXF0Py3 (ORCPT ); Wed, 27 Jun 2007 11:54:29 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:47630 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755420AbXF0Py2 (ORCPT ); Wed, 27 Jun 2007 11:54:28 -0400 Date: Wed, 27 Jun 2007 16:54:25 +0100 From: Al Viro To: Neil Booth Cc: Josh Triplett , Segher Boessenkool , Linus Torvalds , linux-kernel@vger.kernel.org, linux-sparse@vger.kernel.org Subject: Re: [PATCH 16/16] fix handling of integer constant expressions Message-ID: <20070627155425.GX21478@ftp.linux.org.uk> References: <20070624203837.GE21478@ftp.linux.org.uk> <467F531A.3030702@freedesktop.org> <20070626221040.GI21478@ftp.linux.org.uk> <20070626221134.GA21350@ftp.linux.org.uk> <20070627121021.GQ7590@daikokuya.co.uk> <20070627123031.GO21478@ftp.linux.org.uk> <20070627125958.GA16758@daikokuya.co.uk> <20070627131823.GR21478@ftp.linux.org.uk> <20070627133546.GC16758@daikokuya.co.uk> <20070627140636.GT21478@ftp.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070627140636.GT21478@ftp.linux.org.uk> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1510 Lines: 30 On Wed, Jun 27, 2007 at 03:06:36PM +0100, Al Viro wrote: > *unprintable* > > Yes, I see... OK, null pointer constants handling (next patch in the > queue) introduces is_zero_constant() (silent evaluation of integer > constant expression, with division by 0/too large shift/- on lowest > value of signed integer type leaving the branch as-is, so that later > expand would generate a proper error on it; then checking if we'd > reduced the sucker to EXPR_VALUE[0]). I'll pull it into a separate > patch, along with is_nonzero_constant(), and change rules for potential > ICE on parser stage to > maybe-ICE && y => maybe-ICE > maybe-ICE || y => maybe-ICE > maybe-ICE ? x : y => maybe-ICE if at least one of x and y is maybe-ICE > maybe-ICE ? : y => maybe-ICE > letting evaluate_expression() on such suckers use them if the first argument > turns out to be ICE after its evaluate_expression()... > > It really stinks, especially since we can't say "oh, parent it known to > be non-ICE, no need to bother" - subexpression might be shared. ... or it could be done simpler, if we keep the current logics for Int_const_expr flag at parse time and add a 'const expression' one with rules as above. Anyway, I'm going to get some sleep before dealing with that crap. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/